Mobile devices and applications are streaming into enterprises, changing the way IT departments buy technology and relate to other employees, three vendor executives said this week at the MobileBeat conference in San Francisco.

The growing popularity of mobile platforms has forced enterprises to notice and sometimes embrace the kinds of technology that employees are bringing in to work, the CEOs of MobileIron, QuickOffice and Box.net said during a Wednesday panel discussion at the event.

The three vendors are trying to reach small and large companies primarily through their employees, and said interest in their mobile offerings is growing. MobileIron CEO Bob Tinker said his company, which makes mobile device management software, had gained 225 enterprise customers in the past 90 days. Box.net cited a recent 18,000-seat software deal with Procter & Gamble.

The arrival of popular tablets, led by Apple's iPad last year, moved mobile computing by enterprises into high gear, the panelists said.

"I view the tablet as the missing link," said Alan Masarek, CEO of QuickOffice, which sells software for creating and editing Microsoft Office files on mobile devices. On tablets, unlike on smartphones, employees can easily continue to do their work as they move from one device to another, he said.

Box.net, a provider of an online content management service, also saw the iPad's arrival as "a nonlinear event," CEO Aaron Levie said. Construction companies started using Box.net's iPad app on site, and executives started using it while running meetings, he said.

However, there's now more at play than employees bringing their latest toys into the office and wanting to use them for work, Levie said.

"Previously, you had end-users bringing devices in ... but now you have end-users who can bring applications in," he said. Rather than IT departments being sold on a new technology by a vendor that came in to make a deal with the company, now individual employees are adopting Box.net and then getting their enterprises interested in it, Levie said.

As a result, Box.net doesn't have to target companies of a specific size. "Fundamentally, the end users in these organizations are acting and behaving very similarly," Levie said.

As rank-and-file employees introduce new hardware and software and want corporate support for it, with potential productivity benefits for the company, their relationship with the technology specialists changes, MobileIron's Tinker said. IT departments are more willing to work with users and give them what they want.

"It's shifting from a very parental model to much more of an adult relationship," Tinker said.

One reason that relatively new, small vendors can now get access to large companies is that Microsoft, which once dominated many enterprises with the Windows operating system and a full suite of PC applications, has missed many of the new trends of the past few years, the executives said. Rivals such as SalesForce.com have stepped in, changing IT administrators' attitudes, Levie said.

"You're going to mix and match best-of-breed applications instead of just going to one provider for all your solutions," Levie said. Microsoft's foibles have opened up a big opportunity in the mobile arena, as for example the company has only a handful of applications for the entire iPad market, he said.

These upheavals will change the makeup of the enterprise software market for good, in a shift as big as when workers started to demand Internet access at their office PCs in the 1990s, MobileIron's Tinker said.

"I think we're going to look back collectively on 2011 and look at this as the year that mobile IT was born," Tinker said.

Along with this new opportunity will come security challenges, as enterprises shift from assuming internal communications will run over a private network to accepting that most traffic will be on public carrier networks, Tinker said. How to safely divide a single handset between professional and personal uses is another issue, he added. Another challenge will be making mobile software run on multiple, frequently updated operating systems, and work with other mobile applications, Box.net's Levie said.

These kinds of issues are just beginning to be addressed, said Masarek of QuickOffice, who compared the enterprise mobile business to a baseball game.

"We're in batting practice," he said. "We're not even in the first inning."